An electromyographic study on the superior head of the lateral pterygoid muscle during mastication from the standpoint of condylar movement

Abstract

Electromyograms of the superior (SLpt) and inferior (ILpt) heads of the lateral pterygoid muscle were recorded and analysed during mastication, together with the condylar and incisal movements. The SLpt appears to have two phasic functions. In the first phase it controls the position and speed of the disc and condyle as it returns posteriorly to centric position. In the second phase, it functions mainly during the final closing phase on the working side to direct the orientation of masticatory forces toward the articular eminence in response to increases in these forces. These functions are completed by the supplementary activity of the ILpt.